The answer is number one, proof.
The first Monday after the second Wednesday in December after the presidential election
The Congress of Vienna was a meeting held in Austria from late 1814 to june 1815, where ambassadors of different European states (such as <u><em>Great Britain, Russia, Prussia, Spain, Portugal, The Netherlands, France, Sweden, Switzerland) </em></u>chose diplomatically the new borders<u><em>. </em></u>
The meeting was mainly to confirm that France would loss the annexed territories between 1795 and 1810, these territories had been conquered by Napoleon I and the boundaries were remade after the defeat of Napoleon at Waterloo in the period of time that is known as the Hunder days (called like that after the Napoleon's failed attempt to restore his empire).
The purpose wasn't only to give the lands back to their former countries, but also to make arrangemets that would give the nations involved the ideal conditions for growing.
